Year US Dollars adjusted for inflation) 1991 3680.989 1992 3636.259 1993 3705.343 1994 3656.723 1995 3737.898 1996 3853.211 1997 3799.32 1998 3928.608 1999 3886.69 2000 3898.466 2001 3885.956 2002 3865.888 2003 3832.702 2004 3855.429 2005 3944.059 2006 3992.123 2007 4167.717 2008 4201.661 2009 4257.483 2010 4324.175 2011 4443.511 2012 4751.029 2013 4949.607 2014 4943.124 2015 5450.66 2016 5537.581 2017 5673.947 2018 5794.83 2019 5919.18 2020 6040.601 2021 6163.446 2022 6288.707